pendulum used in Moby Dick

a weight hanging from a fixed location so that the weight swings freely back and forth under the influence of gravity — such as is seen in some mechanical clocks

or:

a change that is roughly proportional and in the opposite direction of a prior change — such as a change in opinion

No resolution could withstand it; in that dreamy mood losing all consciousness, at last my soul went out of my body; though my body still continued to sway as a pendulum will, long after the power which first moved it is withdrawn.